The present invention relates to a method of and an apparatus for determining tire shapes by using a non-contact displacement gage. More specifically, the present invention relates to a method of and an apparatus for determining tire shapes, which enable both a reduction in the weight of the apparatus and an improvement in determination accuracy.
Hitherto, the shapes and groove depths of the tread portion of a pneumatic tire have been determined by using a non-contact displacement gage, and the determination values have been used as data for analyzing tread wear characteristics of the tire or the like. As an apparatus for determining tire shapes as described above, a portable compact determination apparatus has been proposed in which a displacement gage (probe) scans a tire tread portion (for example, see Japanese Unexamined Patent Publication No. H5-256738).
However, in the portable determination apparatus reduced in weight, the weight of the displacement gage is relatively large. Therefore, when the displacement gage scans a tire tread portion, the position of the center of gravity of the whole determination apparatus shifts, resulting in a tilt of the determination apparatus and a change in the distance between the tread surface and the displacement gage. Accordingly, a problem arises that the determination accuracy is lowered. For this reason, the whole determination apparatus needs to be made heavy while resultantly sacrificing the lightness, or alternatively, a support needs to be provided to fix the determination apparatus. As a result, determination work requires large amounts of effort and time.